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For 2021 - online Python 3 training - see ((here)).

Our plans were to retire in summer 2020 and see the world, but Coronavirus has lead us into a lot of lockdown programming in Python 3 and PHP 7.
We can now offer tailored online training - small groups, real tutors - works really well for groups of 4 to 14 delegates. Anywhere in the world; course language English.

Please ask about private 'maintenance' training for Python 2, Tcl, Perl, PHP, Lua, etc.
Check your user is human. Have him retype a word in a graphic

Do you have trouble with automated programs completing forms on your websites and making cart loads of submissions? Or even just a few spammers submitting their betting ads, performance enhancing pill sites, and share purchase suggestions? And yet you don't want to have to have anyone who wants to use your site register.

Using what has become known as captcha technology, you can display a graphic with some text on what's basically a login page, then have your human user type that text back in. It's very difficult indeed for automata to recognise the text, and can be doubly so if you vary the background, change fonts between characters and change text colour, scale, rotation. Mind you, you can make it pretty tough for the human too.

You'll find captcha in use already on many big sites, and there are other sites that will host the service for you. Actually, if you've got PHP available and the GD module it's very easy to code it up from first principles and that gives you the ultimate of flexibility.

* Try my demo here
* Show source code of main demo
* Show source code of graphic generator
(written 2006-07-17, updated 2009-01-14)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
H999 - Additional PHP Material
  [54] PHP and natural sorting - (2004-09-19)
  [239] What and why for the epoch - (2005-03-08)
  [320] Ordnance Survey - using a 'Get a map' - (2005-05-22)
  [322] More maps - (2005-05-23)
  [337] the array returned by preg_match_all - (2005-06-06)
  [372] Time calculation in PHP - (2005-07-08)
  [468] Stand alone PHP programs - (2005-10-18)
  [483] Double Dollars in PHP - (2005-11-02)
  [493] Running a Perl script within a PHP page - (2005-11-12)
  [563] Merging pictures using PHP and GD - (2006-01-13)
  [603] PHP - setting sort order with an associative array - (2006-02-13)
  [665] PHP Image viewing application - (2006-04-01)
  [687] Presentation, Business and Persistence layers in Perl and PHP - (2006-04-17)
  [789] Hot answers in PHP - (2006-07-02)
  [822] PHP - a team member leaves - (2006-08-04)
  [839] Reporting on the 10 largest files or 10 top scores - (2006-08-20)
  [917] Syntax checking in PHP - (2006-11-07)
  [937] Display an image from a MySQL database in a web page via PHP - (2006-11-22)
  [1010] Dates, times, clickable diarys in PHP - (2006-12-28)
  [1020] Parallel processing in PHP - (2007-01-03)
  [1053] Sorting people by name in PHP - (2007-01-26)
  [1104] Drawing dynamic graphs in PHP - (2007-03-09)
  [1194] Drawing hands on a clock face - PHP - (2007-05-19)
  [1270] PHP Standalone - keyboard to screen - (2007-07-18)
  [1389] Controlling and labelling Google maps via PHP - (2007-10-13)
  [1390] Converting from postal address to latitude / longitude - (2007-10-13)
  [1391] Ordnance Survey Grid Reference to Latitude / Longitude - (2007-10-14)
  [1451] More PHP sample and demonstration programs - (2007-12-01)
  [1485] Copyright and theft of images, bandwidth and members. - (2007-12-26)
  [1505] Script to present commonly used images - PHP - (2008-01-13)
  [1519] Flipping images on your web page - (2008-01-26)
  [1623] PHP Techniques - a workshop - (2008-04-26)
  [2073] Extra PHP Examples - (2009-03-09)
  [2215] If nothing, make it nothing. - (2009-06-02)
  [2684] Exception handling in PHP - (2010-03-18)
  [3118] Arrays of arrays - or 2D arrays. How to program tables. - (2011-01-02)
  [3210] Catchable fatal error in PHP ... How to catch, and alternative solutions such as JSON - (2011-03-22)
  [4655] Image indexer / thumbnail display scripts in PHP - (2016-02-25)

H304 - PHP - DDA, Style and image handling
  [1506] Ongoing Image Copyright Issues, PHP and MySQL solutions - (2008-01-14)
  [2031] Choosing from an image with an image map - (2009-02-08)
  [2343] World Flags in your PHP pages - (2009-08-10)
  [2539] Changing Images - (2009-12-17)
  [2715] Uploading an image, document or pdf via a browser (php) - (2010-04-10)
  [2917] Upload Image, Store in database, redisplay in browser. PHP and MySQL - (2010-08-12)
  [3747] An easy way to comply with the new cookie law if your site is well designed - (2012-06-02)

G903 - Well House Consultants - Running and moderating forums and social media sites
  [22] Falling out over the silliest things - (2004-08-21)
  [29] Silence is Golden - (2004-08-26)
  [115] Expiration dates or times on web pages - (2004-11-12)
  [130] Spelling and grammar - (2004-11-25)
  [204] The confidence to allow public comments - (2005-02-06)
  [231] Feedback as lifeblood - (2005-02-28)
  [248] Use me, but use me effectively - (2005-03-16)
  [424] How not to run a forum - (2005-08-24)
  [516] Open source questions? Anyone can ask. - (2005-12-03)
  [651] Please Register with Opentalk - but just once! - (2006-03-19)
  [828] Freedom of speech and freedom to post - (2006-08-10)
  [841] Forum help - a push in the right direction - (2006-08-21)
  [919] Freedom for X is denial of privacy for Y - (2006-11-09)
  [923] Why shouldn't I spam? - (2006-11-13)
  [948] Running an on line campaign - (2006-11-27)
  [1088] Why use BBC code not HTML? - (2007-02-21)
  [1190] Save the Forum - A regular clean sweep - (2007-05-17)
  [1362] No Thank You - (2007-09-23)
  [1472] The Horse goes on and on - (2007-12-15)
  [1523] Ive just received an email from myself. Should I be worried? - (2008-01-29)
  [1532] Comment spam blocked. Please comment via Forums - (2008-02-05)
  [1539] A forum is not always the best vehicle - (2008-02-14)
  [1563] Guidlines for posting on a forum - (2008-03-04)
  [1569] I dont care - goodbye - (2008-03-09)
  [1578] Please don't shout at me! - (2008-03-16)
  [1595] First Great Western Weekend - (2008-03-30)
  [1678] Software - changes and delays. But courses must run on time! - (2008-06-15)
  [1759] While the world sleeps ... - (2008-08-19)
  [1923] Making it all worthwhile - (2008-12-04)
  [1972] Pettifog and forum boards away from public view - (2009-01-03)
  [2103] Ask the Tutor - Open Source forum - (2009-03-25)
  [2116] Why do we delay new forum members through authorisation? - (2009-04-03)
  [2156] Stopping forum spam - control of the signup process - (2009-05-04)
  [2162] Admins thoughts on banning a member from a forum - (2009-05-09)
  [2177] Preventing forum spam - checks at sign up - (2009-05-12)
  [2254] Forum membership - a privilege not a right - (2009-06-22)
  [2386] Computing under the influence of alcohol - (2009-08-29)
  [2526] A reluctance to move from old shoes to new - (2009-12-05)
  [2527] Flying tonight - (2009-12-05)
  [2569] How to run a successful online poll / petition / survey / consultation - (2010-01-10)
  [2781] The 500 pound question to get you started - (2010-05-26)
  [2820] Netiquette for forum newcomers - (2010-06-20)
  [3479] Practical Extraction and Reporting - using Python and Extreme Programming - (2011-10-14)
  [3910] Identifying your real customers and keeping them well informed fast - (2012-11-02)
  [4017] Acceptable User Policy / vexatious interacter - (2013-02-24)
  [4025] Backups, Codebase, Strategy and more - dealing with forum incidents - (2013-03-03)
  [4065] Handling requests to a forum - the background process - (2013-04-17)
  [4234] Change to Libel and Defamation laws from 1st January 2014 - (2013-12-31)
  [4239] Facebook marketing - early experiences - (2014-01-19)
  [4283] Can a legitimate forum post become illegal a year later? - (2014-07-11)
  [4307] Identifying and clearing denial of service attacks on your Apache server - (2014-09-27)
  [4315] Welcoming genuine forum posters quickly - but turning away off topic advertisers - (2014-11-16)
  [4403] The unbalanced relationship between customer and provider - (2015-01-21)
  [4492] Almost so wrong, but perhaps it's right for some? - (2015-05-11)

A192 - Web Application Deployment - Firewalls
  [770] Splash! - (2006-06-20)
  [3679] Setting up your Linux system as a firewall using iptables - (2012-04-02)
  [3680] How can I run multiple web servers behind a single IP address? - (2012-04-02)


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Telling large from small
Some other Articles
A bad place for security firms
What to do during a Linux build
Sales call
Telling large from small
Check your user is human. Have him retype a word in a graphic
Melksham Carnival Parade
The Courts, Holt
Not shouting
undefined reference to typeinfo - C++ error message
Simple polymorphism example - C++
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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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